A light is incident on face `AB` of an equilateral glass prism `ABC`. After refraction at `AB`, the ray is incident on face `BC` at the angle slightly greater than critical angles so that it gets reflected from face `BC` and finally emerges out from face `AC`. Net deviation angle of the ray is `112^(@)` anticlockwise. The angle of incidence 'i' has value:
.

Options

A. `22^(@)`
B. `24^(@)`
C. `26^(@)`
D. `28^(@)`

Answer

C

Explanation

Total deviation =`(i-r)+(180-2 theta_(c))+(i-r)=112^(@)`
as `r=60- theta_(c)`
`2i-120+2 theta_(c) +180-2theta_(c) =112^(@)`
`rArr 2i=52^(@)`
`i=26^(@)`